ObjectiveTo evaluate serum Slit2 protein level in patients with chronic severe hepatitis B, and the relation with extent of liver damage and prognosis of patients.MethodsIn FebruaryJuly 2014, patients with chronic hepatitis  B(chronic hepatitis group)  and chronic severe hepatitis  B(chronic severe hepatitis group) in an infectious department were observed, healthy volunteers were as control group, and patients in chronic severe hepatitis group were subdivided into recovery subgroup and nonrecovery subgroup based on whether patients had recovered. Serum Slit2 protein, prothrombin activity(PTA),   total bilirubin (TBIL), and  alanine transaminase（ALT）levels were detected and compared.ResultsA total of 157 patients (chronic hepatitis  group, n=93; chronic severe hepatitis group, n=64) and 10 healthy volunteers were included in the study . Slit2 protein levels were significantly different among three groups（F=5.596，P=0.004）, serum Slit2 protein levels in chronic hepatitis group and chronic severe hepatitis group were (4.90±1.07) ng/mL  and (3.09±1.00)ng/mL respectively, both were higher than (2.10±0.60)ng/mL in healthy control group (both P＜0.05); serum Slit2  protein  level in chronic severe hepatitis group was significantly lower than chronic hepatitis group (P＜0.05). Serum Slit2 protein level in nonrecovery subgroup of chronic severe hepatitis group was significantly lower than recovery subgroup (［1.88±0.67］ ng/mL vs ［2.96±1.32］ng/mL, t=2.319,P=0.032). Serum Slit2  protein  level in patients with chronic hepatitis  B was positively correlated with PTA level(r=0.33，P＜0.05), but negatively correlated with serum TBIL level (r=-0.46，P＜0.05) and ALT level （r=-0.32，P＜0.05）.ConclusionSerum Slit2 protein level is an important index which can reflect the prognosis of patients with chronic severe hepatitis, low serum Slit2 level suggests the poor clinical prognosis.